erratic missfire issues

[Carl H]

ive been slowly shaking down the car for little problems here and there but a rather nasty one has reared its head the past few days.what will happen is the car will drive flawlessly for hours on end but then you can shut it down and upon restart it will missfire and refuse to rev.the strange thing is if you drive long enough it goes away and then drives normally.there is no rhyme or reason as to when and where it will do it and ambient temp or weather does not seem to affect it either.to me this sounds like a sensor failing or possible injector problem...granted it started doing this after i filled up with gas but injector impedence check showed all within spec.i just changed the fuel filter 2 days ago and opened up the tank yet again to check for debris; i suppose its possible to have a clogged filter or bad unit.i plan on checking plugs tommorow but im running out of ideas.any ideas?

[Q45tech]

Important to view CAS outputs at high rpms with a digital oscilloscope as the 360 - 1 degree optical signals have a way of getting ragged from oil vapor/dirt as they age.

The ecu has a backup from 90 degree magnetic sensor but sometimes you get hiccups especially above 3,000 rpm.

I replaced my CAS with a brand new unit around 250k [13 years] and the problems went away, unfortunately the unit cannot be dissassembled fully for cleaning. The J30/300zx has similar high mileage problems.

The 1 degree firing accuracy of the coil on plug system resulted in ~~ 10 HP gain above 6,000 rpm and is necessary at 7300 rpm. Especially with reprogram where 2-3 degrees of advance are added to add power.

Research spark plug/distributor scatter inthat each must be EXACTLY 90 degrees apart for perfection.

This GM pdf is a good read to understand the accuracy required:http://porschehybrids.pbwiki.c...k.pdf

[Carl H]

good info, it is appreciated but i think the problem was the fuel filter i used...it was a brand new puralator unit but it appears to have been either internally blocked or some how clogged in less than 300mi.i just replaced the filter with a brand new nissan filter (which i should have done in the first place) and so far the problem seems to have gone away.inverting the puralator filter no fuel drains out of the top (flow out) but will drain from the bottom.i've got a few spare cas sensors and should it come back i'll toss one on and see if it helps.

[HG50]

hey q45tech. do you have an email address that i cant write to? thanks.